HPV Cancers: Blocking MARCHF8 Protein May Restore Immune Response
A team of scientists at Henry Ford Health + Michigan State University Health Sciences has identified a key mechanism that allows certain head and neck cancers linked to the human papillomavirus (HPV) to evade the body’s immune defenses. This discovery, published in the Proceedings of the National Academy of Sciences, centers on a single protein, MARCHF8, and suggests that blocking its action could restore the immune system’s ability to recognize and destroy these often-treatment-resistant tumors.
For years, clinicians and researchers have observed that HPV-positive head and neck cancers often lack the molecular signals – specifically, MHCI molecules – that alert the immune system to the presence of a problem. Without these “red flags,” the immune system essentially overlooks the cancerous cells. This new research, led by Dohun Pyeon, Ph.D., professor in the Department of Microbiology, Genetics, &. Immunology, pinpoints how HPV hijacks a cellular process to achieve this invisibility.
How HPV Co-opts the Immune System
The study reveals that HPV co-opts a protein called MARCHF8 to dismantle MHCI molecules on the surface of cancer cells. MHCI molecules are crucial for presenting fragments of proteins from within the cell to the immune system, signaling whether the cell is healthy or infected/cancerous. By removing these markers, HPV effectively renders the cancer cells “invisible” to immune surveillance. Researchers found that when MARCHF8 was removed in laboratory models, the immune system was able to identify and clear the tumors, even in cases where standard immunotherapy had failed. This finding is particularly significant given the increasing incidence of HPV-positive head and neck cancers in the United States over the past few decades.
Mohamed Khalil, Ph.D., research assistant professor in the Department of Microbiology, Genetics, & Immunology, and first author on the paper, explained that eliminating MARCHF8 not only suppressed tumor growth but also triggered a more robust anti-tumor immune response. “We found that the MARCHF8 knockout activated T cells and enhanced T cells, natural killer cells, and macrophage infiltration into the tumor microenvironment,” Khalil said. “I think we have very promising hope for targeting MARCHF8.”
The Role of Immune Cell Crosstalk
The research team, collaborating with Henry Ford Health physician-researcher Qing-Sheng Mi, M.D., Ph.D., utilized single-cell RNA-sequencing to analyze the tumor microenvironment with unprecedented detail. This allowed them to map the complex interactions between different immune cells. The analysis revealed that blocking MARCHF8 fundamentally alters immune cell communication, dramatically boosting the activity of cytotoxic CD8+ T cells and natural killer (NK) cells – key players in the immune response against cancer. As detailed in the study, knocking out MARCHF8 increased crosstalk between NK cells, CD8+ T cells, and macrophages, enhancing the overall tumor-killing activity.
“We showed knocking out MARCHF8 fundamentally rewires immune cell crosstalk—dramatically boosting the cytotoxic activity of CD8+ T cells and NK cells,” said Mi. “It revealed not just that the therapy works, but precisely how and why.”
Implications for Immunotherapy
The findings suggest a potential new therapeutic strategy for HPV-positive head and neck cancers. Currently, immunotherapy – treatments that harness the power of the immune system to fight cancer – is not always effective, particularly in “cold” tumors that lack immune cell infiltration. The researchers demonstrated that combining MARCHF8 inhibition with existing immunotherapy drugs could convert these “cold” tumors into “hot” tumors, making them more susceptible to immune attack. This approach offers a potential lifeline for patients who have exhausted other treatment options.
The study also explored the potential of combining MARCHF8 knockout with anti-PD-1 treatment, a common form of immunotherapy. The results showed that this combination further enhanced tumor suppression and increased immune cell infiltration in mice bearing tumors that were resistant to anti-PD-1 therapy alone. This suggests that targeting MARCHF8 could overcome resistance to existing immunotherapies.
Understanding MHC-I and Immune Evasion
The loss of major histocompatibility complex class I (MHC-I) molecules is a well-known mechanism of cancer immune evasion. MHC-I molecules present antigens (fragments of proteins) on the cell surface, allowing the immune system to detect abnormal cells, such as cancer cells. When cancer cells lose MHC-I expression, they become less visible to the immune system. This study provides a crucial insight into the mechanism driving MHC-I downregulation in HPV-positive cancers, identifying MARCHF8 as a key player in this process. Michigan State University’s reporting on the study highlights the significance of this discovery in unraveling a major mystery in cancer immunology.
Future Directions and Clinical Translation
The researchers are now focused on understanding how different immune cells collaborate to kill tumor cells once MHCI markers are restored. Natural killer cells, in particular, appear to play a more significant role than previously appreciated. The ultimate goal is to develop a drug that specifically blocks MARCHF8 in humans, allowing clinicians to combine this new therapy with existing immunotherapies to improve outcomes for patients with treatment-resistant HPV-positive head and neck cancers.
“This could restore the immune system’s ability to recognize and destroy these tumors in combination with existing immunotherapies,” said Mi. “It would allow doctors to offer a lifeline to patients with tumors that currently resist all other treatments.”
The team plans to further investigate the interplay between immune cells and the tumor microenvironment to optimize the therapeutic strategy. This research holds promise for not only HPV-positive head and neck cancers but potentially other cancers that utilize similar immune evasion mechanisms.